Trading kidneys, repugnant markets and stable marriages win the Nobel Prize in Economics

Roth and Shapley charted a course for economists to go beyond simply arguing for markets in everything.

The 2012 Nobel Prize in Economics - technically the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel, but nobody cares - has been awarded to two American Economists, Alvin Roth and Lloyd Shapley "for the theory of stable allocations and the practice of market design". The Nobel Committee explains what that means:

This year's Prize concerns a central economic problem: how to match different agents as well as possible. For example, students have to be matched with schools, and donors of human organs with patients in need of a transplant. How can such matching be accomplished as efficiently as possible? What methods are beneficial to what groups? The prize rewards two scholars who have answered these questions on a journey from abstract theory on stable allocations to practical design of market institutions.

Lloyd Shapley used so-called cooperative game theory to study and compare different matching methods. A key issue is to ensure that a matching is stable in the sense that two agents cannot be found who would prefer each other over their current counterparts. Shapley and his colleagues derived specific methods – in particular, the so-called Gale-Shapley algorithm – that always ensure a stable matching. These methods also limit agents' motives for manipulating the matching process. Shapley was able to show how the specific design of a method may systematically benefit one or the other side of the market.

Alvin Roth recognized that Shapley's theoretical results could clarify the functioning of important markets in practice. In a series of empirical studies, Roth and his colleagues demonstrated that stability is the key to understanding the success of particular market institutions. Roth was later able to substantiate this conclusion in systematic laboratory experiments. He also helped redesign existing institutions for matching new doctors with hospitals, students with schools, and organ donors with patients. These reforms are all based on the Gale-Shapley algorithm, along with modifications that take into account specific circumstances and ethical restrictions, such as the preclusion of side payments.

Even though these two researchers worked independently of one another, the combination of Shapley's basic theory and Roth's empirical investigations, experiments and practical design has generated a flourishing field of research and improved the performance of many markets. This year's prize is awarded for an outstanding example of economic engineering.

The committee have yet again reaffirmed the old adage that the most important thing to do when trying for a nobel prize is to live long enough that your achievements are recognised. The Gale-Shapley algorithm, for instance, was devised in 1962, when Lloyd Shapley was 34. It concerns a maths problem known as the stable marriage problem: if you have an even number of men and women, can you always come up with a set of marriages where there are no two people of opposite sex who would both rather have each other than their current partners? (1960s maths problems: usually heteronormative.) If you can, then the marriage is "stable".

The Gale-Shapley algorithm is a way of always ensuring stable matches; and much of Shapley's work covers the same areas, straddling the boundaries between economics, mathematics, and computer science.

Roth is the younger of the two winners, and works in a far more empirical sphere. As the committee points out, although the two men never actually collaberated, Roth took Shapley's theoretical work and applied it to actually existing markets. For instance, Roth used the Gale-Shapley agorithm to ease the kidney shortage in the US. David Wessel explains (£):

As of noon yesterday, 58,470 people in the U.S. were waiting for a kidney transplant. Most won't get one this year. There aren't enough donated kidneys to go around. Surgeons transplanted just 15,129 kidneys last year. Now a band of transplant surgeons and economists are trying to fix that by creating a moneyless market for exchanging kidneys. Most transplanted kidneys come from a person who has died, a supply that grows slowly because of ignorance about the need for donations or grieving relatives' reluctance. But a kidney taken from a live donor works better, and almost everyone has a spare. As techniques improve for removing healthy kidneys and for suppressing the body's tendency to reject a transplant, doctors increasingly turn to kidneys from living donors, usually relatives. Last year, 43% of kidneys transplanted in the U.S. came from living donors, up from 28% a decade ago. But a biological barrier often blocks a transplant from a relative. In about a third of all would-be pairs, blood types are incompatible. In others, the sick person has antibodies that can initiate a rejection of the donated organ. It's heartbreaking "to have the treasure of the live donor and then have that not go forward because of a biological obstacle," says Massachusetts General Hospital transplant surgeon Francis DelMonico.

Occasionally, transplant centers spot a way out: One New England father with blood type A couldn't donate a kidney to his daughter with blood type B. So he gave a kidney to a teenager with blood type A, and the teenager's sister gave a kidney for the man's daughter. New England's transplant centers have done six such exchanges. Baltimore's Johns Hopkins University has done seven.

The crucial thing about Roth's work, from an economic point of view, is that it involves finding stable allocations using market-like situations without involving money. The kidney swaps in the New England situation are market-like, trading kidneys for kidneys in a way that makes all parties better-off, but they don't actually require kidneys to be bought and sold.

We can see the importance of this by looking at another paper of Roth's, not cited by the committee, on repugnance in markets (pdf). Roth demonstrates that some markets are limited because the very existance of a market in some goods is considered repugnant. He argues, for instance, that the trade in horse meat being banned in California is not done through fears that eating horse meat is unsafe; nor is it done for animal welfare reasons, since it is still legal to farm and kill horses. But banned it is, and Roth argues that the natural response of economists to situations of this type - to argue for freer markets - is wrong, since it ignores the very strong feelings involved in the situation. Instead:

Being aware of the sources of repugnance can only help make such discussions more productive, not least because it can help separate the issues that are fundamentally empirical—like the degree of crowding out of altruistic donations that might result from different incentive schemes compared to how much new supply might be produced—from areas of disagreement that are not primarily empirical.

Hopefully his new Nobel Prize should give that argument greater weight in the years ahead.

A patient receives a kidney in Johns Hopkins university in Baltimore. Photograph: Getty Images

Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.

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There is nothing compassionate about Britain’s Dickensian tolerance of begging

I was called “heartless” for urging police to refer beggars to support services. But funding drug habits to salve a liberal conscience is the truly cruel approach.

In Rochdale, like many other towns across the country, we’re working hard to support small businesses and make our high streets inviting places for people to visit. So it doesn’t help when growing numbers of aggressive street beggars are becoming a regular fixture on the streets, accosting shoppers.

I’ve raised this with the police on several occasions now and when I tweeted that they needed to enforce laws preventing begging and refer them to appropriate services, all hell broke loose on social media. I was condemned as heartless, evil and, of course, the favourite insult of all left-wing trolls, “a Tory”.

An article in the Guardian supported this knee-jerk consensus that I was a typically out-of-touch politician who didn’t understand the underlying reasons for begging and accused me of being “misguided” and showing “open disdain” for the poor. 

The problem is, this isn’t true, as I know plenty about begging.

Before I became an MP, I worked as a researcher for The Big Issue and went on to set up a social research company that carried out significant research on street begging, including a major report that was published by the homeless charity, Crisis.

When I worked at The Big Issue, the strapline on the magazine used to say: “Working not Begging”. This encapsulated its philosophy of dignity in work and empowering people to help themselves. I’ve seen many people’s lives transformed through the work of The Big Issue, but I’ve never seen one person’s life transformed by thrusting small change at them as they beg in the street.

The Big Issue’s founder, John Bird, has argued this position very eloquently over the years. Giving to beggars helps no one, he says. “On the contrary, it locks the beggar in a downward spiral of abject dependency and victimhood, where all self-respect, honesty and hope are lost.”

Even though he’s now doing great work in the House of Lords, much of Bird’s transformative zeal is lost on politicians. Too many on the right have no interest in helping the poor, while too many on the left are more interested in easing their conscience than grappling with the hard solutions required to turn chaotic lives around.

But a good starting point is always to examine the facts.

The Labour leader of Manchester City Council, Richard Leese, has cited evidence that suggests that 80 per cent of street beggars in Manchester are not homeless. And national police figures have shown that fewer than one in five people arrested for begging are homeless.

Further research overwhelmingly shows the most powerful motivating force behind begging is to fund drug addiction. The homeless charity, Thames Reach, estimates that 80 per cent of beggars in London do so to support a drug habit, particularly crack cocaine and heroin, while drug-testing figures by the Metropolitan Police on beggars indicated that between 70 and 80 per cent tested positive for Class A drugs.

It’s important to distinguish that homelessness and begging can be very different sets of circumstances. As Thames Reach puts it, “most rough sleepers don’t beg and most beggars aren’t rough sleepers”.

And this is why they often require different solutions.

In the case of begging, breaking a chaotic drug dependency is hard and the important first step is arrest referral – ie. the police referring beggars on to specialised support services.  The police approach to begging is inconsistent – with action often only coming after local pressure. For example, when West Midlands Police received over 1,000 complaints about street begging, a crackdown was launched. This is not the case everywhere, but only the police have the power to pick beggars up and start a process that can turn their lives around.

With drug-related deaths hitting record levels in England and Wales in recent years, combined with cuts to drug addiction services and a nine per cent cut to local authority health budgets over the next three years, all the conditions are in place for things to get a lot worse.

This week there will be an important homelessness debate in Parliament, as Bob Blackman MP's Homelessness Reduction Bill is due to come back before the House of Commons for report stage. This is welcome legislation, but until we start to properly distinguish the unique set of problems and needs that beggars have, I fear begging on the streets will increase.

Eighteen years ago, I was involved in a report called Drugs at the Sharp End, which called on the government to urgently review its drug strategy. Its findings were presented to the government’s drugs czar Keith Hellawell on Newsnight and there was a sense that the penny was finally dropping.

I feel we’ve gone backwards since then. Not just in the progress that has been undone through services being cut, but also in terms of general attitudes towards begging.

A Dickensian tolerance of begging demonstrates an appalling Victorian attitude that has no place in 21st century Britain. Do we really think it’s acceptable for our fellow citizens to live as beggars with no real way out? And well-meaning displays of “compassion” are losing touch with pragmatic policy. This well-intentioned approach is starting to become symptomatic of the shallow, placard-waving gesture politics of the left, which helps no one and has no connection to meaningful action.

If we’re going make sure begging has no place in modern Britain, then we can’t let misguided sentiment get in the way of a genuine drive to transform lives through evidenced-based effective policy.

Simon Danczuk is MP for Rochdale.